I have an '06 4WD, 6-speed manual, 3.73, no mods (I am adding gauges). I am now over 40K miles and often get over 20 MPG. I can get 12-15 MPG pulling my 12, 000 lbs 5th wheel. I would suggest you find the source of your poor mileage before making any mods or adding a tuner. As stated, start with having the dealer reflash the ECM.

 

I run My edge/w additude, on the milage setting, and im getting around 20MPG hand calc. onl have 17800 on the truck.

 

Hand calc 18.5 in town.. Looks like it's going to be around 20 on the highway - after the intake and bed cover.. Edge isn't on yet.

 

I was getting about 16-17 in town unloaded. The milage didn't start getting better untill 20K (truck never worked hard) . Then it got about 17-18 in town 19 fwy. I added Smarty JR and am now getting 18-19 in town and 20-21 on the road (flat ground no load) running the smarty @ tow setting (70+ HP). I towed my 30 foot travel trailer the other day and got 15-16 (smile) all MPG are overhead comp. OH and 4.11 rear gearing

 

With the Smarty Jr, I can get more than 25 if I baby it, keep it under 63, slow down up hills, speed up down hills... Just cruising I will get 24 -23 depending on wind.... Once I put my foot in it the mileage can drop with the Smarty! If I keep turbo boost under 4 lbs, I get amazing mileage... Keeping the auto in Tow/Haul helps lock the converter and boosts mileage. If I need 8 - 10 lbs of boost, I'll drop to 20 mpg, 12 lbs gets me 18 mpg. Around town is not what kills me, but cold starts and hills get me.

The other day I drove empty into a 50 mph wind doing 70, and I was getting 14 mpg.

 

I'm averaging around 15 MPG. On the highway I'll maybe see 17, winter time in city probably 14. Lift and big tires I'm sure are not helping...

 

In the winter 14-15 in town, 17-19 on highway depending on the wind (empty). 3500lb enclosed trailer 14-16 highway. 35" tires & 4" lift.

 

My 06 gets 15.5-16 mpg avg hwy with a best( and never once got even close to again) of 16.98 mpg ,however my beat up, poorly serviced 03 get's a minimum of 18 (75 mph plus) and as much as 21 hwy. Both trucks pull heavily and the 06 gets a new air filter,fuel filter and tires rotated every 9-10k miles.

 

I was a little skeptical about the "engine break-in and your milage will go up theory"....???

Last summer the best I could do was about 19.5 driving 65 hwy. I get really bad city/winter milage due to winter blend and short trips with lots of stops, around 11mpg. I did not calculate my milage much this winter but I took a few 200 mile round trips this spring (still on winter blend) and my milage is about 22 hand calculated, WOW. I just turned 23000 miles.

 

i just took a trip to baltimore, 120 miles each way, babying the truck coasting where i can on hills and cruising 62mph i got 21mpg with a banks 6 gun pda on level 5 and i only have 14,000 miles on it now, but i hook a trailer to it my 24 ft enclsoe with micro sprint and tools it goes down to like 11-12, maybe when it breaks in it will fix it self or just brake